T4+5: SEX-LINKED INHERITANCE

ex of plant that has no sex chromosomes

pea plants

karyotype

individuals full set of chromosomes

homomorphic

homologues share the same form since they have the same size and shape

e.x homologous chromosomes

how many chromosomes are autosomes

44

what is the 23rd pair of chromosome

sex chromosomes

heteromorphic

they have very different size and shape and carry different genes

• many genes that are on the x but not the y

why are X and Y homologous pairs

• their sequence are similar near the centromere

• sequence at the tips of both chromosomes that carry the same genes

what happens when a XY person undergoes meiosis to makes sperm

• each sperm cell receives 1 of each autosome (1-22)

• receives 1 sex chromosome: X or Y

what happens when an XX person undergoes meiosis to make ova

• each ovum recives 1 of each autosome (1-22)

• each ovum receives 1 of the two X chromosomes

heterogametic

they make gametes with different-looking karyotypes

• XY people

homogametic

all eggs have similar karyotypes

• XX people

autosomal genes

genes found on autosomes

sex-linked genes

genes found on sex chromosomes

X-linked genes

genes on the X chromosome

Y-linked genes

genes on the Y chromosomes (not the X)

A mutated Y-linked gene would affect who?

only affects XY people and passed on to all XY offsprings